五台山不同海拔林线森林斑块内草本群落与表层土壤特征

The Understory Herbage Community and Surface Soil Characters at Different Altitudes of Treeline Forest Patch in Wutai Mountain

该文选择五台山4个海拔梯度(2200 m、2250 m、2300 m、2350 m)的林线森林斑块为样地,对其林下的草本层和表层土壤(0~10 cm)进行野外调查取样和室内实验研究,运用指数、单因素方差分析、PERMANOVA分析、PCoA排序以及Pearson相关和Spearman秩相关进行分析.主要结果有:(i)在林线森林斑块内草本群落物种多样性在样地间差异不显著,但草本群落差异性显著受海拔梯度的影响.海拔2350 m和2300 m的2个样地群落物种组成相似性最小且群落相似性最小,海拔2300~2350 m引起了草本群落较大的变化.而海拔2250 m和2200 m的2个样地群落物种组成相似性最大,且群落相似性中等.推测海拔2200~2250 m的变化引起了物种地位的变化;(ii)单因素方差分析表明表层土壤pH值、全氮、全磷和全硫在不同海拔的林线森林斑块内呈显著变化,秩和检验结果表明有机碳在海拔梯度间变化不显著,全氮、全硫和有机碳的变化随海拔升高而增大;(iii)Pearson相关和Spearman秩相关的研究结果表明,土壤pH值与全氮、全硫、全磷和有机碳呈显著负相关,全氮、全硫、全磷和有机碳之间大多数呈显著正相关,这些土壤理化性质与植物多样性的相关性不显著.研究发现:在林线森林斑块内草本群落的海拔间变异受土壤理化性质的影响不显著,受海拔影响显著但变化趋势波动性较大,这可能与放牧和其他环境因子的影响有关,需设置更严格的控制实验来进一步分析.

The four altitudes(2200 m,2250 m,2300 m,2350 m)are selected as sites at treeline patch,the herbage and surface soil(0—10 cm)are investigated and indoor experiment is made.Indexes,one-way ANOVA,PERMANOVA,PCoA,and Pearson correlation and Spearman rank correlation coefficients are used for analysis.The results are as follows.(i)Species diversity has no significant difference between sites,but herbage community is significantly affected by altitude.Comparing herbage communities in site with 2350 m and 2300 m,it shows that they have both minimal of community component similarity and community similarity,it has experienced greatest community difference from 2300 m to 2350 m.While comparing two sites with 2250 m and 2200 m,community component similarity is greatest and medium of community similarity,it means that important values of species change more than community component from 2200 m to 2250 m.(ii)One-way ANOVA analysis shows that surface soil pH,total nitrogen,total phosphorus and total sulfur have significant difference between sites,Kruskal Wallis rank sum test shows that soil organic carbon have no significant difference between sites,and total nitrogen,total sulfur and organic carbon increase with altitude getting higher.(iii)Considering results from Pearson and Spearman correlation coefficients,it shows that soil pH has negative correlation with total nitrogen,total phosphorus and total sulfur and organic carbon in surface soil,most of correlation between total nitrogen,total phosphorus,total sulfur and organic carbon are positive,these soil properties have no significant with species diversity.It is found that understory herbage community in treeline forest patch fluctuates and is affected with altitude,not soil properties,the reason may be from grazing and other environmental conditions,more strict experiment shall be set for deep research.